This invention relates to a device for automatically closing windows with vertically sliding sashes, in the case of fire.
Windows are known comprising at least one sash vertically movable along guides between a lower closed position and an upper open position.
In order to facilitate the raising of the sash during opening and to stabilise the raised position reached, it is known to connect the sash to a pair of counterweights by corresponding cords passing about idle pulleys fitted to each upper corner of the window. Both the counterweights and the relative cords are slidingly housed in corresponding longitudinal compartments provided in the side sections of the cased frame of the window.
Devices for fitting to said windows in order to automatically close them in case of fire are also known. These known devices consist essentially of thermal sensors interposed in the cord portion between the window and counterweight and arranged to break the continuity of said cord when a predetermined temperature is exceeded. When a fire occurs, the temperature increase causes the sensors to act by breaking the continuity of the relative cord with the result that the balancing effect of the two counterweights on the window no longer exists and the sash automatically falls if in the raised position.
The drawback of this automatic window closure device is that it requires the use of a counterweight balancing system for the sash, i.e., a system which is bulky because of a its length and requires the use of channels of adequate crosssection to contain and guide them.
Spring compensator devices are also known for balancing the weight of the vertically sliding sashes. They consist essentially of a small-diameter tubular element internally housing a coil spring operating torsionally and fixed at its upper end to said tube and at its lower end to a cylindrical terminal axially immobile to the tube but free to rotate with respect to it. This cylindrical terminal comprises a diametrical slot traversed by a helically twisted metal strip. For use, the tubular element is fixed to the vertical channel or channels of the cased frame of the window, and the lower end of the helically twisted strip is fixed to the mobile sash while in the raised position. When the sash is lowered it causes the strip to emerge axially and, because of the fact that it cannot rotate as it is fixed to the sash, causes the cylindrical terminal to rotate and load the spring. When the window is closed, i.e., the sash lowered, the spring of the (or of each) balancing device is thus in a loaded state, and this facilitates the subsequent raising of the sash. In fact, the sash is generally provided with means for fastening it in its closed position, and when these are released they allow the sash to rise spontaneously.
These known spring compensators are considerably more advantageous than counterweight compensators because by being of smaller size they do not require the use of large channels and can substantially be installed within the interspace between the sash and cased frame in conventional windows. They also have the great advantage of being adjustable and allowing perfect balancing of the window independently of its weight.
However, known spring compensators cannot be used in fire-protected windows because in contrast to counterweight compensators their method of operation is such as to keep the sash raised in the absence of external streses.
An object of the invention is to provide a device which in the case of fire will automatically close vertically sliding sash windows which use conventional spring compensators.
A further object of the invention is to provide a device of the aforesaid type which can be easily installed in windows, including conventional windows.
A further object of the invention is to provide an operating device which can be easily inspected and reactivated after it has acted.